The human immunodeficiency virus (“HIV”) is the causative agent of acquired immunodeficiency syndrome (“AIDS”), a disease characterized by the destruction of the immune system, particularly of CD4+ T-cells, with attendant susceptibility to opportunistic infections, and its precursor AIDS-related complex (“ARC”), a syndrome characterized by symptoms such as persistent generalized lymphadenopathy, fever and weight loss.
(3R,3aS,6aR)-hexahydrofuro[2,3-b]furan-3-ol represented by the formula (I) is a useful as intermediate for synthesis of compounds for an anti-AIDS drugs.

WO 01/25240, EP 539192-A, and Tetrahedron Letters, 1995, Vol. 36, p. 505 are discloses a process for synthesizing a racemic BIS-Tetrahydrofuran compound of formula IV using tributyltin hydride and ozone oxidation. These reagents are more hazardous and using for plant scale not suitable.
WO03024974A2 discloses the preparation of formula I is based on a photochemical cycloaddition reaction to give an oxetane intermediate which is subjected to a reduction, deprotection and rearrangement reaction. This process is cost-inefficient due to the low yields, the requisite of expensive equipment for the photochemical. This process also involves resolution in the final part of the synthesis.
US 20050256322 A1 discloses the key intermediate, an O-protected hydroxyacetyl-γ-butyrolactone, is asymmetrically hydrogenated and subsequently reduced, deprotected and cyclized to give the undesired diastereomer of compound of formula I. Further converted into desired isomer using oxidation/reduction reaction to get desired isomer. This process involve more number of steps and highly cost-inefficient.
The present invention encompassed herein an improved, commercially viable and industrially advantageous process to achieve with improved yield and purity of (3R,3aS,6aR)-hexahydrofuro[2,3-b]furan-3-ol of formula I using novel intermediates.